The present invention relates to a data recording/reproducing optical disk, a master disk manufacturing apparatus for an optical disk used in manufacture of the optical disk and an optical disk recording/reproducing apparatus (hereinafter simply referred to as optical disk apparatus as well) using the optical disk.
Recently, a digital video disk (DVD) as an optical disk of a large storage capacity has been developed and an optical disk apparatus which is used for recording data on the optical disk and reproducing the recorded data thereon has also been developed.
An optical disk used in such an optical disk apparatus has a format such that a surface of the optical disk is partitioned along a radial direction, into a plurality of annular zones comprising a plurality of tracks. Each zone has the same number of sectors in one track therein and the number of sectors in one track in a zone is increased by one between adjacent two zones toward the outer side of the optical disk and this is applied through all the zones along a radial direction.
The above described optical disk apparatus is designed so as to perform only recording at an almost fixed linear speed (laser light from an optical head travels at an almost constant moving speed along a track on the optical disk) according to characteristics of the optical disk. For this reason, a different rotation number is adopted for a different zone when data is recorded. That is, a rotation number of the disk is sequentially decreased as the laser light travels in recording along a radial direction from an inner side zone to the outer side zone on the optical disk.
Besides, when data is reproduced, a rotation number along a radial direction is changed from the inner zone to the outer zone in a similar manner to the recording.
In such an optical disk apparatus, a data transmission rate is different in a different zone when reproducing is performed.
Therefore, when an animation is recorded as data and the data are reproduced, there is a need for circuitry through which a transmission rate is adjusted so as to assume the same value since a transmission rate is different in a different zone. In such a case, the transmission rate is adjusted to the lowest rate, which entails a problem: the transmission rate thus adjusted is slow.